Blog Archive

Monday, 3 March 2008

Weekly BioNews 25 Feb - 3 Mar 2008

- Device Allows Scientists To Control Gene Activity Across Generations Of Cells

ScienceDaily (Mar. 3, 2008)

Just as cells inherit genes, they also inherit a set of instructions that tell genes when to become active, in which tissues and to what extent. Now, Rockefeller University researchers have built a device that, by allowing scientists to turn genes on and off in actively multiplying budding yeast cells, will help them figure out more precisely than before how genes and proteins interact with one another and how these interactions drive cellular functions.

Pausing cell division. Using a new device, scientists administer pulses of a gene-regulating chemical to budding yeast cells as they multiply.

“A slight disturbance in the abundance of a single protein can affect the functioning of a cell dramatically,” says Gilles Charvin, a postdoc who works with both Eric Siggia, head of the Laboratory of Theoretical Condensed Matter Physics, and Frederick Cross, head of the Laboratory of Yeast Molecular Genetics. “So, we wanted to devise a way to supply a single cell with a controlled pulse of protein at any time and then see how the cell would respond,” he says.

- Gene That Controls Ozone Resistance Of Plants Could Lead To Drought-resistant Crops

ScienceDaily (Feb. 29, 2008)

Biologists at the University of California, San Diego, working with collaborators at the University of Helsinki in Finland and two other European institutions, have elucidated the mechanism of a plant gene that controls the amount of atmospheric ozone entering a plant’s leaves.

Mammalian-like Neurogenesis In Fruit Flies

Their finding helps explain why rising concentrations of carbon dioxide in the atmosphere may not necessarily lead to greater photosynthetic activity and carbon sequestration by plants as atmospheric ozone pollutants increase. And it provides a new tool for geneticists to design plants with an ability to resist droughts by regulating the opening and closing of their stomata—the tiny breathing pores in leaves through which gases and water vapor flow during photosynthesis and respiration.

The nerve cells in the brain of Drosophila are generated by neural stem cell-like progenitor cells called neuroblasts. In the currently accepted model of neurogenesis, these neuroblast divide asymmetrically both to self renew and to produce a smaller progenitor cell. This smaller cell then divides only once into two daughter cells, which receive cell fate determinants, causing them to exit the cell cycle and differentiate into postmitotic neural cells.

In the mammalian brain, neural stem cells may also divide asymmetrically but they can then amplify the number of cells they produce through intermediate progenitors. These intermediate progenitors can divide repeatedly in a symmetrical manner, such that each intermediate progenitor gives rise to a number of postmitotic neurons in the brain. A research team from the Biozentrum set out to study whether specific Drosophila neuroblasts might also be able to increase the number of cells generated in the postembryonic brain via a similar mechanism.

Exposed skin cells weather conditions harsh enough to mutate DNA. To keep these mutations from spreading, evolution has found a way to keep these cells from proliferating. Rockefeller University and HHMI researchers have now discovered evolution's solution: a tiny strand of RNA. But the research's implications go deeper, and may also suggest how healthy cells elsewhere in the body can turn cancerous.

Every minute, 30,000 of our outermost skin cells die so that we can live. When they do, new cells migrate from the inner layer of the skin to the surface of it, where they form a tough protective barrier. In a series of elegant experiments in mice, researchers at Rockefeller University have now discovered a tiny RNA molecule that helps create this barrier. The results not only yield new insight into how skin first evolved, but also suggest how healthy cells can turn cancerous.

Investigators at St. Jude Children’s Research Hospital have discovered a dance of proteins that protects certain cells from undergoing apoptosis, also known as programmed cell death. Understanding the fine points of apoptosis is important to researchers seeking ways to control this process.

In a series of experiments, St. Jude researchers found that if any one of three molecules is missing, certain cells lose the ability to protect themselves from apoptosis. A report on this work appears in the advance online publication of “Nature.”

“This is probably the first description of what is happening mechanistically that contributes to the ability of cells to delay apoptosis,” said James Ihle, Ph.D., the paper’s senior author and chair of the St. Jude Department of Biochemistry. “It provides incredible insights into how three proteins work and how they can control apoptosis.”

Bacteria mutate for a living, evading antibiotic drugs while killing tens of thousands of people in the United States each year. But as concern about drug-resistant bacteria grows, one novel approach under way at the University of North Carolina at Chapel Hill seeks to thwart the bug without a drug by taking a cue from nature.

Mark Schoenfisch and his lab of analytical chemists at UNC have created nano-scale scaffolds made of silica and loaded with nitric oxide (NO) – an important molecule in mammals that plays a role in regulating blood pressure, neurotransmission and fighting bacterial infections, among other vital functions.

“There was evidence that nitric oxide kills bacteria, but the difficult part involved storing it in a manner such that it could be delivered to bacterial cells,” said Evan Hetrick, a doctoral student in Schoenfisch’s lab and lead author on a paper in the February issue of the American Chemical Society’s journal ACS Nano.

Using artificial cell-like particles, Yale biomedical engineers have devised a rapid and efficient way to produce a 45-fold enhancement of T cell activation and expansion, an immune response important for a patient’s ability to fight cancer and infectious diseases, according to an advance on line report in Molecular Therapy.

The artificial cells, developed by Tarek Fahmy, assistant professor of biomedical engineering at Yale and his graduate student Erin Steenblock, are made of a material commonly used for biodegradable sutures. The authors say that the new method is the first “off-the-shelf” antigen-presenting artificial cell that can be tuned to target a specific disease or infection.

“This procedure is likely to make it to the clinic rapidly,” said senior author Fahmy. “All of the materials we use are natural, biodegradable already have FDA approval.”